In a prior art film splicer, a predetermined number of packages, after being filled with a content and transported from a filling machine, are collected in a packed pattern and wrapped with a thermally-shrinkable film, e.g., a polyethylene film.
In this case, the film is formed into a continuous configuration and wound into a roll of film Which is set on a feeder. Then, the film delivered from the feeder is continuously fed to a shrinking machine, where the film is cut into a length required for use in wrapping.
If the roll of film is emptied of film during continuous wrapping, a second roll of film (which will be referred to as a new roll hereinafter) is set on the feeder, and a second film is delivered from the new roll. However, the wrapping of the packages is continuously conducted in the shrinking machine and therefore, the prior art film splicer is of a construction such that a portion of the second film in the new roll near its leading end can be connected to a portion of the first film near its trailing end delivered from the first roll of film (which will be an old roll hereinafter) and thus, continuously supplied to the shrinking machine.
FIG. 1 is a diagram for explaining the operation of a prior art film splicer, wherein FIG. 1a illustrates a state before the connection, and FIG. 1b illustrates a state after the connection.
In FIG. 1, reference numeral 11 is an old roll; reference numeral 12 is a first film delivered from the old roll by a feeder which is not shown; reference numeral 14 is a new roll; and reference numeral 15 is a second film delivered from the new roll 14 by the feeder which is not shown. While the first film 12 is being delivered from the old roll 11, the new roll 14 is previously set on the feeder, as shown in FIG. 1a, and the positioning of a leading end of the second film 15 is conducted.
Reference numeral 18 is a ultrasonic sensor disposed on a transporting path for each of the films 12 and 15 for detecting a portion of each delivered film 12, 15 near a trailing end thereof; reference numerals 20 and 21 are a pair of heaters disposed in an opposed relation to each other for movement toward and away from each other. If the ultrasonic sensor 18 detects a portion of the first film near its trailing end, a control unit which is not shown allows the heaters 20 and 21 to be moved. The heaters 20 and 21 clamp and heat the portion of the first film 12 near its trailing end and the portion of the second film near its leading end to perform a heat-sealing of them at a connection point a, as shown in FIG. 1b. In this manner, the second film 15 can be connected with the first film 12. Reference numeral 12a is a residual portion formed rearwardly of the connection point a of the first film 12.
In the prior art film splicer, however, when the second film 15 is to be connected with the first film 12, the control unit starts the movement of the heaters 20 and 21 at a timing such that the portion of the first film 12 near its trailing end is passed through the ultrasonic sensor 18, thereby performing such connection.
However, the amount of first film 12 delivered varies depending upon the packed pattern of the collected packages and for this reason, it is difficult to position the portion of the first film 12 near its trailing end between the heaters 20 and 21 in conducting the heat sealing, and a residual portion 12a may be formed rearwardly of the connection point a, as described above.
If the second film 15 is delivered with the residual portion remaining formed, a machine used at a next step is not normally operative. Thereupon, before the residual portion enters the machine used at the next step, it is necessary to stop the machine and remove the residual portion.
Accordingly, it is an object of the present invention to provide a film splicer, wherein the problems associated with the prior art film splicer are overcome, and in connecting the first film in the old roll and the second film in the new roll with each other, a residual portion cannot be formed rearwardly of the connection point of the first film, and the machine used at the next step need not be stopped.